Methods of processing uncured rubber and like raw materials, and article therefor

ABSTRACT

The processing of uncured rubber or like raw material, which is normally produced, stored and shipped in sheet form but which is to be subjected to a continuous and uniform strip feeding into an extruder, mill or like treating apparatus, is disclosed. For this purpose, there is provided in a sheet of such material a plurality of slits extending across the sheet and spaced from each other longitudinally of the sheet, the slits in an alternating sequence starting at the opposite side edges of the sheet and each terminating short of the respective other side edge of the sheet. When one end portion of the slit sheet is introduced into the bite of the apparatus, the sheet is subjected to a pulling force and separates along the slits into a continuous zig-zag strip. Apparatus for slitting the sheet in the indicated manner is also disclosed. This abstract is not to be taken either as a complete exposition or as a limitation of the present invention, however, the full nature and extent of the invention being discernible only by reference to and from the entire disclosure.

United States Patent Harris 1 1 METHODS OF PROCESSING UNCURED RUBBER ANDLIKE RAW MATERIALS, AND ARTICLE THEREFOR Related US. Application Data[60] Division of Ser. No. 65,673, Aug. 20, 1970, which is a continuationof Ser. No. 537,474, March 25, 1966,

abandoned.

[52] US. Cl 241 /30, 83/1 [51] Int. Cl. B026 23/02 [58] Field of Search83/1, 156,244, 355;

[56] References Cited UNITED STATES PATENTS 2,397,415 3/1946 Ghez et al161/118 3,032,337 5/1962 Holman 83/51 X 3,503,289 3/1970 Friberg 83/1[111 3,738,58 51 June 12, 1973 Primary Examiner-Granville Y. Custer, Jr.Attorney-Norbert P. Holler [57] ABSTRACT The processing of uncuredrubber or like raw material, which is normally produced, stored andshipped in sheet form but which is to be subjected to a continuous anduniform strip feeding into an extruder, mill or like treating apparatus,is disclosed. For this purpose, there is provided in a sheet of suchmaterial a plurality of slits extending across the sheet and spaced fromeach other longitudinally of the sheet, the slits in an alternatingsequence starting at the opposite side edges of the sheet and eachterminating short of the respective other side edge of the sheet. Whenone end portion of the slit sheet is introduced into the bite of theapparatus, the sheet is subjected to a pulling force and separates alongthe slits into a continuous zig-zag strip. Apparatus for slitting thesheet in the indicated manner is also disclosed. This abstract is not tobe taken either as a complete exposition or as a limitation of thepresent invention, however, the full nature and extent of the inventionbeing discernible only by reference to and from the entire disclosure.

10 Claims, 4 Drawing Figures Patented June 12, 1973 3,738,580-

2 Shuts-Sheet l Patented June 12, 1973 3,738,580

2 Sluts-Shut 2 METHGDS OF PRQCESSTNG UNCUREID RUBBER AND LIKE RAWMATERTALS, AND ARTICLE THEREFOR This application is a division of myprior copending application Ser. No. 65,673, filed Aug. 20, 1970, whichin turn is a continuation of my prior copending application Ser. No.537,474, filed Mar. 25, 1966 and now abandoned.

This invention relates to improvements in the art of processing uncuredrubber and like raw materials.

When natural or synthetic uncured rubber stocks or like raw materialsare being processed in a mill, extruder or like treating apparatus, theyare generally fed into the apparatus in the form of either relativelylarge irregularly shaped slabs or elongated strips previously formed bysuitably cutting up sheets of such material. Whereas the processor ofthe raw material normally desires to have it in slab or strip form, theproducer of such materials, who is usually confronted by a shipping andstorage problem, prefers to have the material in sheet form, sinceneither irregularly shaped slabs nor elongated continuous strips ofsubstantial length can be packaged as compactly and economically aspossible, i.e., without an undue waste of space. A further disadvantageencountered is that when such material to be processed is in slab orsheet form, it is difficult to feed it uniformly into the apparatus soas to assure the uniformity of the treatment.

It is an object of the present invention, therefore, to provide novelmethods and means of processing uncured rubber or like raw materialwhich enable the aforesaid disadvantages to be substantially eliminated.

A more specific object of the present invention is the provision ofnovel and improved means and methods enabling the raw material, thoughproduced in the form of relatively wide sheet stock, to be readilytransformed into continuous strip stock lending itself to a continuousand uniform feeding into the apparatus.

Generally speaking, the objectives of the present invention are attainedby slitting a sheet ofsuch raw material transversely in an alternatingsequence in from the opposite side edges of the sheet, each slitterminating short of the respective other side edge of the sheet. Whenan end portion of such a slit sheet is then introduced into the bite ofthe apparatus while the same is in operation, the sheet is subjected toa pulling force and separates along the slits into a continuous zig-zagstrip.

The foregoing and other objects, characteristics and advantages of thepresent invention will be more clearly understood from the followingdetailed descrip tion thereof when read in conjunction with theaccompanying drawings, in which:

FIG. I is a fragmentary top plan view of an apparatus for producingcontinuous strip stock from a sheet thereof to be processed inaccordance with the principles of the present invention;

FIG. 2 is a fragmentary side elevational view of the apparatus shown inFIG. l; and

FIGS. 3 and 4 diagrammatically illustrate two ways of utilizing thestrip stock formed by the said apparatus.

Referring now first to FIGS. 1 and 2, according to the preferred aspectsof the present invention the apparatus for cutting sheet stock S ofuncured rubber or like raw material into continuous strip stockcomprises a rotary cutter lll driven by any suitable means (not shown)and journalled in parallel cooperative relation to a rotatable backuproll 112. The cutter 111 is provided with a plurality of essentiallylongitudinally extending, peripherally spaced blades l3 which are shownas being curved in the manner of an ogee. The blades 13, of which theremust be an even number, are alternatingly recessed at one end, as shownat 13, so that each cutting edge effectively starts at one end of thecutter ill and terminates somewhat short of the other end thereof. Thetwo members ill and 12 are adjustably preloaded toward each other, e.g.,by springs or other suitable means (not shown) to permit the sheet stockS passing therebetween to be penetrated to a predetermined extent by theactive cutting; edge portions of the blades 13. Both the cutter and theback-up roll are preferably made of metal, e.g., stainless steel or thelike, with the roll l2 further having an outer covering T2 of a suitableelastomeric material, e.g., cast polyurethane.

In the operation of the apparatus lltl, the sheet stock S is fed intothe bite of the assembly by means of a suitable conveyor arrangement Mand is there subjected to the cutting action of the blades 13, which atthe same time feed it through the nip of the members ill and 12. It willbe readily understood that only the portion of each blade 13 which isnot recessed will penetrate into the sheet stock S, and that any portionof the latter which underlies a recessed portion. 113' of a given bladewill not be cut by that blade. The arrangement may, of course, be so setthat the sheet stock S will be entirely out through, or, for a reason tobe explained presently, that the sheet stock will be only partially'cutthrough so as to leave an unpenetrated sheet thickness of, say about0.003 to 0.004 inch or so. The sheet stock S which has passed the cutterllll is transported away by a further suitable conveyor arrangement l5and is seen to be provided with a plurality of obliquely oriented,parallel, transverse slits 16 extending in an alternating sequence infrom the opposite side edges of the sheet and each terminating, as shownat 16, short of the respective other side edge of the sheet. The cutsheet stock S thus is seen to be composed of a continuous zig-zag strip(see also FIG. 3) in which the connections between adjacent parallelreaches ll7 are constituted by the unsevered portions T7 of the sheet.

It will be understood that the present invention can be utilized in avariety of ways. Thus, the apparatus 10 can be more or less intimatelyassociated with an apparatus lid (FIG. 3), for example an extruder usedto extrude tread slabs or strips for tires, so that once the leading endof the strip stock 17 has been fed into the extruder, the pulling forceexerted by the latter on the strip automatically opens the sheet stock Sinto the desired strip form, thereby ensuring a continuous and uniformadmission of stock into the extruder. In such a case, the sheet stock Smay be either fully or partly cut through, as previously described,since even if the latter of these conditions obtains, the unpenetratedsheet thickness in the regions of the slits 116 is insufficient toprevent the sheet sections 17 from being pulled apart into the desiredstrip form. Quite obviously, the original sheet stock S fed into theapparatus 10 may be fed to the latter either directly from a sheetingmill on the like (not shown) or from a package or bale (not shown) inwhich it was shipped (in properly soaped or stearatecoated condition) tothe operator of the extruder. This latter arrangement would be highlyadvantageous, for

example, for a retreader who could feed the sheet stock shipped to himby a rubber producer first out of the bale right into the cutterassembly and thence directly into the extruder. The foregoing wouldapply equally well, of course, if the device 18 were a mill or otherprocessing apparatus rather than an extruder.

Alternatively, if the apparatus is located in the plant of a rubberproducer, the latter may feed the stearated sheet stock S taken from amill or other storage facility into the apparatus 10 to form the cutsheet stock S which then in its unextended form, i.e., merely as slitsheet, may be packaged (FIG. 4) in a standard bale 19 or on a truck forstorage and/or shipment. For this purpose it might actually bepreferable (although not necessarily essential) that the sheet stocks Sbe only partly cut through, since this might make it easier to handlethe sheet during the baling or unbaling operations. The ultimate user ofthe strip stock, e.g., a retreader, is then in a position to feed thestrip 17 directly from the bale into the extruder, tests having shownthat the cut sheet stock S does not tend to reknit along the slits 16between adjacent strip reaches 17 during storage and shipment.

It is to be understood that the foregoing description of preferredaspects of the present invention is for purposes of illustration only,and that a number of changes and modifications in the structural andoperational fea tures and relationships disclosed may be made withoutany departure from the spirit and scope of the present invention asdefined by the hereto appended claims. Thus, the blades 13 on the cutter11 need not be ogeecurved as shown but could be linear instead, andobviously the sheet stock may be cut so that the slits 16 extendsubstantially at right angles to the side edges of the sheet rather thanobliquely as shown. Also, the sheet feed may be intermittent andeffected by means other than the cutter itself. Other variations willreadily suggest themselves to those skilled in the 'art.

Y Having thus described my invention, what I claim and desire to protectby Letters Patent is:

1. The method of processing uncured rubber or like raw material in anextruder, mill or like treating apparatus, comprising the steps ofproviding a sheet of such material, transversely partially slitting saidsheet in an alternating sequence in from the opposite side edges thereofover the entire length of said sheet so that each slit terminates shortof the respective other side edge of said sheet, juxtaposing said sheetto said apparatus, introducing a portion of said sheet adjacent thelocation of the proximate endmost slit into the bite of said apparatuswhile the latter is in operation, whereby said sheet is subjected to alongitudinal pulling force and caused to separate along the slits into acontinuous, relatively narrower, zig-zag strip as said portion of saidsheet and the following portions continuous therewith are drawn intosaid apparatus, thereby achieving a uniform strip feed of said materialinto said apparatus, and continuing the operation of said apparatus tosubject said material to the processing treatment.

2. The method of claim 1, wherein the slitting step is carried out so asto orient the slits obliquely to said side edges of said sheet.

3. The method of claim 1, wherein the slitting step is carried out so asto orient the slits substantially perpendicularly to said side edges ofsaid sheet.

4. The method of claim 1, wherein the slitting comprises cuttingentirely through the thickness of said sheet.

5. The method of claim 1, wherein the slitting step comprises cuttingonly partly through the thickness of said sheet so that the unseveredsheet thickness is insufficient to prevent separation of thestrip-shaped regions bounded by said slits upon application of thepulling force to said sheet.

6. The method of processing uncured rubber or like raw material in anextruder, mill or like treating apparatus, comprising the stepsofjuxtaposing said material to said apparatus in the form of a sheetwhich is provided over the entire length thereof with a plurality oftransverse slits spaced from one another longitudinally of said sheetand in an alternating sequence beginning at the opposite side edges ofsaid sheet and each terminating short of the respective other side edgeof said sheet, introducing a portion of said sheet adjacent the locationof the proximate endmost slit into the bite of said apparatus while thelatter is in operation, whereby said sheet is subjected to alongitudinal pulling force and caused to separate along the slits into acontinuous, relatively narrower, zig-zag strip as said portion of saidsheet and the following portions continuous therewith are drawn intosaid apparatus, thereby achieving a uniform strip feed of said materialinto said apparatus, and continuing the operation of said apparatus tosubject said material to the processing treatment.

7. The method of claim 6, wherein said sheet is provided with slitsoriented obliquely to said side edges of said sheet.

8. The method of claim 6, wherein said sheet is provided with slitsoriented substantially perpendicularly to said side edges of said sheet.

9. The method of claim 6, wherein said sheet is provided with slits cutentirely through the thickness of said sheet.

10. The method of claim 6, wherein said sheet is provided with slits cutonly partly through the thickness of said sheet so that the unseveredsheet thickness is insufficient to prevent separation of thestrip-shaped regions bounded by said slits upon application of thepulling force to said sheet.

2. The method of claim 1, wherein the slitting step is carried out so asto orient the slits obliquely to said side edges Of said sheet.
 3. Themethod of claim 1, wherein the slitting step is carried out so as toorient the slits substantially perpendicularly to said side edges ofsaid sheet.
 4. The method of claim 1, wherein the slitting comprisescutting entirely through the thickness of said sheet.
 5. The method ofclaim 1, wherein the slitting step comprises cutting only partly throughthe thickness of said sheet so that the unsevered sheet thickness isinsufficient to prevent separation of the strip-shaped regions boundedby said slits upon application of the pulling force to said sheet. 6.The method of processing uncured rubber or like raw material in anextruder, mill or like treating apparatus, comprising the steps ofjuxtaposing said material to said apparatus in the form of a sheet whichis provided over the entire length thereof with a plurality oftransverse slits spaced from one another longitudinally of said sheetand in an alternating sequence beginning at the opposite side edges ofsaid sheet and each terminating short of the respective other side edgeof said sheet, introducing a portion of said sheet adjacent the locationof the proximate endmost slit into the bite of said apparatus while thelatter is in operation, whereby said sheet is subjected to alongitudinal pulling force and caused to separate along the slits into acontinuous, relatively narrower, zig-zag strip as said portion of saidsheet and the following portions continuous therewith are drawn intosaid apparatus, thereby achieving a uniform strip feed of said materialinto said apparatus, and continuing the operation of said apparatus tosubject said material to the processing treatment.
 7. The method ofclaim 6, wherein said sheet is provided with slits oriented obliquely tosaid side edges of said sheet.
 8. The method of claim 6, wherein saidsheet is provided with slits oriented substantially perpendicularly tosaid side edges of said sheet.
 9. The method of claim 6, wherein saidsheet is provided with slits cut entirely through the thickness of saidsheet.
 10. The method of claim 6, wherein said sheet is provided withslits cut only partly through the thickness of said sheet so that theunsevered sheet thickness is insufficient to prevent separation of thestrip-shaped regions bounded by said slits upon application of thepulling force to said sheet.